Reversing vision loss by turning back the aging clock
Aging has implications for a wide range of diseases. Researchers have been looking for ways to halt the aging process for millennia, but such methods remain elusive. Scientists at Harvard Medical School have now offered a glimmer of hope that the aging clock in the eye could be reversed—at least in animals.
By reprogramming the expression of three genes, the Harvard team successfully triggered mature nerve cells in mice eyes to adopt a youthful state. The method reversed glaucoma in the mice and reversed age-related vision loss in elderly mice, according to results published in Nature.
If further studies prove out the concept, they could pave the way for therapies that employ the same approach to repair damage in other organs and possibly treat age-related diseases in humans, the team said.
The researchers focused on the “Yamanaka factors,” which are four transcription factors—Oct4, Sox2, Klf4 and c-Myc. In a Nobel Prize-winning discovery, Shinya Yamanaka found that the factors can change the epigenome—how genes are turned on or off—and can thereby transform mature cells back to a stem cell-like state. It has been hypothesized that changes to the epigenome drive cell aging, especially a process called DNA methylation, by which methyl groups are tagged onto DNA.
Past researches have tried to use the four Yamanaka factors to turn back the age clock in living animals, but doing so caused cells to adopt unwanted new identities and induced tumor growth.
In their study, the Harvard researchers dropped the c-Myc gene in hopes of sidestepping the safety problems while still promoting a youthful profile in mouse cells.